There are plenty of comic book-based superhero shows among the current television lineup, with many networks trying their hand at tapping into the popular genre in recent years. While ABC and Netflix's Marvel Comics shows tie into the larger Marvel Cinematic Universe, DC Comics properties like Gotham and Lucifer largely exist on their own. Then there's The CW's trio of DC superhero shows - Arrow, The Flash, and Legends of Tomorrow. These series were established in a shared universe, but in the past few months it was revealed that they also exist within a multiverse along with CBS's Supergirl.
The shows solidified this multiverse in a recent episode of Supergirl, titled 'Worlds Finest,' which saw The Flash's Barry Allen (Grant Gustin) travel to a separate universe from his own and stumble across Kara Danvers (Melissa Benoist). Now, The Flash showrunner Andrew Kreisberg has teased the existence of Kara Danvers in Barry's home universe.
In an interview with EW, Kreisberg confirmed there is a version of Kara on Earth-1, and she would likely have superpowers as well (though a different costume). Check out Kreisberg's full quote:
"Any Kara that exists on Earth-1 would also have to have been an alien. It can’t just be Kara Danvers from Poughkeepsie. … Sure, different costume, but sure."
EW additionally hints that The Flash's Earth-1 version Kara could be DC Comics superhero Power Girl, an alternate universe version of Kara Zor-L who goes by Karen Starr rather than Kara Danvers. The character has appeared alongside Supergirl in the comics, and even starred in a run titled Worlds' Finest - one of two comic series within the DC library with similar titles that Supergirl referenced with its crossover episode.
Though this largely seems to be speculation that Power Girl could appear alongside Barry Allen down the line, Kreisberg and The Flash/Supergirl executive producer Greg Berlanti have already floated the possibility of reversing the previous crossover and having Supergirl or Benoist appear on The Flash. Additionally, given the ratings spike Supergirl saw with 'Worlds Finest' - and the boosts granted to The Flash and Arrow in the past during their crossover events on The CW - it seems possible the networks would be willing to work with the showrunners and actors to make even more crossovers happen.
Of course, there's still one uncertain factor that will impact future crossovers: whether Supergirl will continue on after its first season. The CW has already granted renewals to its entire slate of shows, including Arrow, The Flash, and Legends of Tomorrow. Supergirl, on the other hand, was rumored to be in line for a second season, but CBS has yet to make it official. Although unofficial indicators seem to point toward a renewal for Supergirl, if the show isn't renewed, perhaps Supergirl or Power Girl could become a part- or full-time hero on Earth-1. But, until we receive any officially confirmation about the Sueprgirl renewal or future crossovers, how exactly CBS and The CW's DC Comics multiverse progresses remains to be seen.
Supergirl season 1 will continue with ‘Myriad’ on Monday, April 11th at 8pm on CBS. The Flash returns with ‘Versus Zoom’ on Tuesday, April 19th at 9pm on The CW.